Motor-control system.



T. VARNEY;

MOTOR CONTROL SYSTEM.

APPLICATION FILED AUG.27. 1913.

1,175,669. Patented Mar. 14,1916

wnussszs: yams M BY d 7% ATTORNEY trrrrnn @FIEICE.

" VARNEY, OF PITTSBURGH 1G AND BIANUFACTUBING CC Application filed August :27, 1913.

c all whomii may concern:

Be it l-mown that I, Tnnooonn thinner.-

of the United States, and a resi- Pittsburgh, in the county of Alla gheny and State of Pennsylvania, have ini d a new and useful Improvement in niotorilontrol Systems, of Which the. following is a specification.

My invention relates to motor control sys tems and it has special reference to such systems as are employed in connection with cranes, hoists and similar machinery.

My invention has for one of its objects to provide a system of the character indicated above which is so arranged as to inuniform operation in to enable the operator speed at which the load. is

a citizen 5 lowering a load and to control the lowered.

Another object of my invention is toproride a system of motor control in whiclra magnet brake is automatically rendered inciiective during the operationv ofhm erin' th load, the speed being controlled dynamic braking action of the motor;

A further object of my invention is to provide a system which is entirely automatic in'its operation to stop the motor and its load in case of interruption of the current supply from any cause.

In the operation of cranes or similar machinery, it isv essential that the load he lowered Without shock and that the speed, although under the control of the operator, f can never become dangerously high. It is also an ess ntial feature of such devices that the motor and its load be stopped automa cally when the current supply is interrupted.

A diiliculty has been encountered fore, in systems of this character in that actuating coil of the magnet brake. who is usually in series with the motor is sutliciently energized to prevent the enga 'e merit of the brakewhen the motor urn i:

reduced to decrease the s u he brake con rol.

N thus interferes with the electrical the motor. 7

tion comprises, broadly a motor opted to operate as a serie isting andas a shunt me.

a load. A

J PARTY-5',

A, A SIGNOR TO JVESTINGHO'USIE} 3. t'ZOiiE-TPORATIQN 0F PENNSYLVANIA.

Patented Mar. 14, 1916. Serial No. 786,820.

lever controls the power circuit of the m0- tor in hoisting and controls the dynamic ranking action of the motor in lowering the 'ihe magnet coil or the brake is supplied ih current during the operation of lowering by a circuit which is entirely independent of the dynamic braking circuit oi the motor. This arrangement insures that the brake will not operate While the motor connected for dynamic braking, regardless of the amount of current employed to operate the motor.

The details of my invention Will be described in connection with the accompanying drawings in which Figure l an end View, in elevation, of a controller. Fig. 2 is a View in central vertical section of the controller of Fig. l. a diagrammatic View of circuits apparatus embodying my invention. a diagrammatic view of a simplified arrangement of the motor circuits.

Referring particularly to Figs. 1 and 2,

her 1 comprises a ring of stationary 75 contact segments :2, that are mounted upon and insulated by a suitable supporting body member As shown in Fig. 3, the segments '2 are connected to sections 4 of re sistors 5. 6. and S which constitute Whatthe controller resistance. structure of the controller a shaft 9 and a spider 10 that is mounted upon the shaft and is provided with four arms 11 and a handle 12. Each er arm 11 carries a contact piece 13 oacts with one quadrant of the segcontrol. the corresponding resuitable blow out coil 14 is pron each controller arm.

. cuit connections of the system are h master switch 36 comprising ups of contact segments 15 and 16 no-unted upon the shaft 9 to coact pending stationary contact finand 18. The system comprises '5 19, 20, 21-, 23 and 24., shown .lillllillflllly in Fig. 4 and. controlled master switch 36. Referring now to a m I01.

one

l which c the armature of which is .35 and the field Winding at 26,

in circuit with the variable controller resistors 5, 6, 7 and 8. The motor shaft 27 is provided with a brake wheel 28 which is adapted to be engaged by a brake shoe 29. A spring- 30 normally draws the brake shoe 29 toward the brake wheel 28 and amagnet 31, which coniprises a coil 32 and a core member. 33, h olds the brake shoe 29 away from the wheel28 when the coil 32 is energized. i

When the lever 12 is shifted to the hoist position, the switch 21 is closed and the remaining switches are open.. Current then flows from a positive linc' conductor 34 through resistors 5 and-6,-master switch 36,

conductors 37' and 38, armature 25, comductors 39, resistors 7 and 8, the field wind: ing 26, brake magnet coil 32 and inductor 51 to a negative line conductor 5. The

motor then operates as a series iotor to hoist the load. The b 'ake ma n coil 32 is energized to draw the core member 33 downwardly and thereby render the brake ineffect ve when current is flowing in the -motor circuit. The sections i of the several resistors 5, 6, 7 and 8 are gra. ually cut out as the motor speeds up. JV hen the lever 12 is shifted to the olf p0:

sltion, the motor circuit is broken" and the coil 32 is deiinergized, thereby allowing the brake 29 to be set. are closed and the remaining switches are open. The maximum dynamic braking circuit of the motor, which is thereliy completed, extends from the armature 525 through conductors 3%), alt), 4-1, 42 and 4-3, series field "winding 26, conductors l4, 4'5 and 46 to the motor armature. Any movement of the motor and its load is thus opposed by both a mechanical brake and the dynamic braking effect'of the motor.

When the-lever handle 12 is moved to the lower position: the switches 19, and 24: are closed and the remaining switches are open. Current then flows fromthe line conductor 34 through the resistors 5 and 6, master switch 36, conductors and 39, armature 25, conductors 38 and 37, master switch 36, conductor 47, resistor 48, con.- ductor 44-, brake coil 32 and conductor 51 to the line conductor 35. The field circuit extends from the armature throughconductors 39, resistors '7 and 8, conductor -13,

field winding 26, conductor 4%. resistor 4-8,

conductor 4'7, master switch 36 and conductors 3?:and 88 to the armature 25. The motor now operates in the reverse d rection as a shunt motor to lower the load.-

The speed is controlled by the resistors '5', 6, 7 and 8, the first two of which operate to vary thearmature current and the latter two operate to vary the current traversing the shunt field winding :26. The brake magnet coil 32' is suppliedwrith current through a circuit extending from the hne conductor 3%, hrough a resistor elf), master switch 36, con- The switches 20 and 22' ductors 50 and ii, brake coil 32 and con ductor 51 to the line conductor 35. The brake coil is thus supplied with current inde'- pendently of the motor circuit so that the brake is not effective during the operation of lowering-the load. The'speed is maintained substantially uniform by the dynamic braking of the motor. lhe braking circuit is the same as traced above for the field circuit. lYhen the load tends to cause the motor to rotate at a. higher speed than that for which the controller handle is set, the counter electromotive force of the motor rises and thereby causes'less current to pass through the armature and more current .to pass through the field windin In case the speed of the motor reaches a rate at whichits counter electromotivc force equals the line oltage, no current flows through the brake coil-32 from the motor armature.

The brake coil is then supplied entirely by the auxiliary circuit above described.

Should the current supply fail from any cause whatever, the brake magnet coil 32 will be deenergized and the brake will be set immediately it will be noted that the coil 32 is not included in the dynamic brake circuit of the motors This arrangement permits the coil 32 to operate independently of the circuit conditions of the motor.

While not specifically indicated as such, the conductors 4H, 39, 51, 43, and 38 constitute the trolley wires commonly employed in cranes and hoists. It will be noted,therefore, that l have provided a simple and efficient system in which only five trolley wires are necessary.

it Is understood that such changesand modifications may be made in my invention position, to connect said field winding in shunt relation to said armature and connect said coil in series relation tosaid armature.

2. In a control system for electric motors, an electric motor having an armature and a fieldwinding, a inagnetic brakeliaving; a coil, and a controller so arranged when in one position, as to connect said field windin' I conneef'sa d co l in series with saidarmain shunt to said armature and to Lure-and said field winding and, when-in a second position, to connect saidcoil and said field winding in series with said armature.

3. in a control system for electric motors, an electric motorhaving an. armature auda- P neld winding, magnetic brake having a coil, and a controller so arrange a s to c0nsubscribed my name this 20th day of Aunect szud field Wmdmg elfiher 111 enes o r m gust 1913. parallelwlth sald armature and to mam- T T w tain the connection of said c oil-in serieswith THLODORQ VARDE 5 said armature in the operative positions of Witnessesz.

said controller. ELMER C. HAMMERLE,

. In testimony whereof, I have hereunto P. C. SWAN. 

